A recent NIH Consensus Statement (JAMA 1999 282:974) noted that 70-90,000 Americans each year incur long-term substantial loss of function from traumatic brain injury (TBI). The panel further noted that "the more problematic consequences involve the individual's cognition, emotional function, and behavior." The present studies are aimed at developing pilot data to guide a controlled trial for the use of deep brain stimulation technologies in selected TBI patients: those with recovery limited to regained consciousness, minimal self-awareness, and minimal interpersonal communication. Study patients will either be in a minimally conscious state (MCS) or have emerged from a MCS but remain incapable of independent activities of daily living as measured by the Disability Rating Scale. Emergence from MCS is suggested by reliable and consistent demonstration of functional interaction. Many of these patients demonstrate preserved, but fluctuating, capacities for basic communication, memory, attention, intention, and awareness of self and environment. These observations provide clinical evidence that their limited functional capacities do not represent entirely irreversible damage. The immediate goals of the proposed studies are to define appropriate clinical and imaging criteria and outcome measures to evaluate patients for selection into deep brain stimulation studies, and to evaluate physiological measures that can aid the design of stimulation parameters. We present preliminary neuroimaging data both from patients in chronic vegetative states, and from patients with other neurological conditions with implanted deep brain stimulators that demonstrate selective functional brain activations during neurostimulation. We detail potential strategies for selection of patients and for choosing targets within the thalamic intralaminar nuclei of these patients for electrical stimulation. The strategy of selection of patients for neuromodulation of impaired cognitive function will be evaluated via neuroimaging tools and neuropsychologic evaluation. The proposal combines the unique clinical expertise and experience of neurological, functional stereotactic neurosurgical, and neurorehabilitation investigators. To achieve these goals we will develop a strong multi- disciplinary team with recognized expertise in both investigational and therapeutic studies of brain injured patient populations. The long-range goal of the studies proposed here is to provide a foundation for rational therapies for chronic cognitive disabilities following complex brain injuries.